Recording amplitude meter for dynamic balancing machines



May 14, 1929. F. 'r. M DONOUGH RECORDING AMPLITUDE METER FOR DYNAMIC BALANCING MACHINES 4 Shets-Sheet 1 Original Filed Aug. 14, 1926 May 14, 1929. F. T. McDONOUGH 1,712,508

RECORDING AMPLITUDE METER FOR DYNAMIC BALANCING MACHINES 4 sheets shet 2 Original Filed Aug. 14, 1926 jazz/42% J May 14, 1929. F. T. MCIEDONOUGH 1,712,503

RECORDING AMPLITUDE METER FOR DYNAMIC BALANCING MACHINES Original Filed Aug. 14, 1926 4 Sheets-Sheet 3 L25 M/ l/mad, W? r May 14, 1929. MCDQNOUGH 1,712,508

RECORDING AMPLITUDE METER FOR DYNAMIC BALANCING MACHINES Original Filed Aug. 14, 1926 4 Sheets-Sheet 4 Patented May 14, 19229.

.UNITED STATES j 1,712,508 PATENT OFFICE.

FRANCIS T. MGDONOUGH, F MADISON, WISCONSIN, ASSIGNOR TO GISHOLT MACHINE COMPANY, OF MADISON, WISCONSIN, A CORPORATION OF WISCONSIN.

RECORDING AMPLITUDE METER FOR DYNAMIC BALANCING MACHINES.

Original application filed August 14,; 1926!, Serial No. 129,236. Divided and this application V 10, 1927. Seria1 N0. 225,132. v

In an application heretofore filed by me on the 14th day of August, 1926, Serial -No. 129,236, I have disclosed and claimed an improved dynamic balancing machine comprising generally a resiliently pivoted bration pointer frictionally controlled so as y to remain in fixed position at the point on the scale corresponding to the maximum vibration of the frame after the test has been completed, and thus enable the maximum vibration thus recordedto be easily read.

Balancing machines of this type as heretofore used have been equipped with an indicator in the nature of a fixed scale and an oscillating pointer, the latter being so connected to the pivoted support carrying the test body as to vibrate over the scale syn' chronously and proportionately with the vibrations of the support as shown in Letters Patent to Newkirk No. 1,557,268, October 13, 1925; but in the performance of anactual test, the vibrations of the scale pointer are so rapid that it is a matter of diiiiculty for even the trained eye of a skilled operative to observe and note the point of maximum amplitude of vibration as shown by the indicator. With a view to eliminating this difficulty in thepractical use of these machines, my present invent-ion has, as an important object thereof, the provision of an improved meter which will make a record or fixed showing of the maximum amplitude of vibration, so that the operative may be relieved of the usual strain of observing the same at the instant of its occurrence and making a note thereof for future use. My present application constitutes a division of my former application hereinabove I identified, and, as stated; has for one object thereof, to provide, for use with a balancing machine of the type referred to, a delicate,

accurate and reliable recording amplitude.

meter. Another object of the present invention is to provide an accurate and eflicient means for translating the oscillating movements of the pivoted Work support into exactly proportional movements of the amplltude pointer of the meter; and a still further object is to provide a simple and eiiicient device in the meter itself for fixing or recording the maximum extent of" vibration have in the accompanying drawings and in the subjoined description shown and described the improved amplitude meter in association With a dynamic balancing machine such as it is intended to serve; and referring to the drawings-- Fig. 1 is aperspect-ive elevation of a dy nan'nc balancing machine of the type above referred to, equipped with my improved recording amplimeter;

Fig. 2 is an enlarged front elevation of the amplimeter and its immediate support, the latter including means by which the meter may be set to indicate a neutral or rest iQOSflOH of the test body support when under 3 is an enlarged vertical axial section, from front to rear, of the meter, its housing and supporting frame;

Fig. 4 is a sectional detail on the line H of Fig. 3;

Fig. 5 is a sectional detail on 'the'line 5- of Fig. 3;

Fig. 6 is a vertical section in a plane at right angles to that of Fig. 3, taken on the line 66 of the latter figure;

Fig. 7 is a front elevation of. the meter box or casing,'with the front wall thereof removed; p

Fig. 8 ma horlzontal section on the line 88 of Fig.7; I

Fig. 9 is a top plan detail of a portion of the arbor, showingthe manner of'attaching the cords thereto;

Fig. 10 is an end elevation of Fig. QVlQ/WQC l from the right.

Referring first to filed October Figs. 1 and andbriefl describing the principal elements of the galancing machine, 10 designates a heavy foundation or .base plate on which is rigidly mounted a vertical yoke frame 11. On the upper end of the frame 11 are mounted a pair of plate spring pivots 12 to the upper edges of which are clamped supporting members 13 that carry a rectangular frame 14 designed to have a vertical swinging or vibrating movement on the pivots 12. One end of the frame 14 is adjustably connected by a screw 15 to a goose neck spring 16 carried on the free end of a cantilever spring'17 rigidly mounted at one end on a supporting frame 18 mounted on the foundation orbase plate. 10. Longitudinally adjustable at the left end of frame 14 is a headstock frame 19 on which is journaled a fly wheel 20.

At longitudinally spaced points on the frame 14 are standards 21 in which are journaled anti-friction rollers 22 that form supports for the test body, such for instance as the engine crank shaft indicated at S. The shaft of the fly wheel carries a suitable chuck or adapter 23 that engages with one end of the test body to rotate the latter.

The revolving parts are set in motion by hand or power friction applied to the'periphery of fly wheel '20. At 24 is indicated an electric motor mounted on the base 10, the armature of which is belted to a friction pulley engaged with the fly wheel 20 and so mounted that it may be engaged and disengaged with the pulley 20 through a pedal 25, whereby the pulley may be at first robracket 26 tated to a speed beyond the critical speed, and may be then released from the driving agency and permitted to slowly run down through the critical speed without disturbing the natural vibration of the frame 14. It will be observedthat in the machine above briefly described the anti-friction bearings 22 that support the test body are located on opposite sides of and at different distances from the vertical transverse plane of the spring pivots 12. This makes it possible, as is described in the Newkirk patent above-identified, by reversing the position of the test body on its supports to cause.

two different planes of the body, substantia-llyat right angles to.its axis of rotation, to successively lie in the perpendicular axial plane of said spring pivots, whereby the amount of unbalance inboth ofsaid planes may'be determined, in accordance with the known fact that complete dynamic balance, including static balance, can be accomplished by correction-to the rotative body in two arbitrarily chosen angles to, the axis of rotation.

At one corner of the base 10 is a pedestal on WhiCil is rigidly mounted a vertical s cketed to receive a post 27 and also formed with an .arm 28 carrying -a planes at right attached thereto by angle brackets 37 (Fig.

6) and fastening screw s 38, and a front wall 39 conveniently formed integral with the rim wall having a large central opening 40 covered by'a glass plate 41. Attached to the back plate 36 by a pair of upper horizontal posts 42 and a pairof lower horizontal posts 43 is a dial frame plate 44 fitting the rim wall 35 intcriorly and having a central circular opening 45 in rear of and connnensurate with the front opening 40. lVithin this opening 45 and occupying the plane of the frame plate 44 is the dial disc 46 of the meter mounted and supported at its lower portion on and by four horizontal posts 47 connecting the same to the back plate 36.

On the back plate 36 is a central tapped boss 48 in which is mounted a threaded plug 49 forming one bearing member for the main arbor of the meter; the inner end of the plug 49 being chambered and preferably fitted with a jewel bearing 50, and its rear end having a kerf 51 for convenient adjustment by a screw-driver. Attached to the dial disc 46 is a bearing block 52 suitably chambered to receive a jewel bearing 53.' In the jewel bearings and 53 is mounted the main central arbor 54, keyed to which is the sleeve or hub 55 of a fourarm spider 56 (see Fig. 6). Fitted onto arbor 54 and adjustably attached to oppositelyextcnding arms of the spider 56 by screws 57 is the indicating pointer 58, the upper endportion of which is rectangularly bent, as shown at 59 and extends through the annular slot 60 (Fig. 7 formed between the edge of the opening 45 and the periphery of the dial plate 46; the forwardly bent end 59 of the indicating pointer preferably carrying a pointer tip 61 overlying a graduated scale 46' on the scale disc. On the heel end of the pointer 58 is a small counterweight 58' (Fig. 3) designed to secure a perfect balance of the pointer on its arbor.

Attached to the arbor 54,

referably in the manner clearly indicated in Figs. 3, 9

and 10. are two cords 62 and 62', spaced I some distance apart on the arbor, that are maintained .under constant tension.v The upper end of the cord 62 is connected through a ring 63, to the lower end of a pull spring 64, this latter being anchored at its 36 with capacity of vertical adjustment bya pair of screws 73 extendingthrough a vertical slot 74 in the back plate. Attached to and depending from the head 69 is a rod 75.forming, in effect, an extension of the rod 68, and extending through a bushing 76 mounted in the bottom of the rim wall 35 and forming an adjustable stop to limit the oscillation of the arbor 'and the swing of the pointer in one direction, as hereinafterw explained. To the lower end of rod is attached a tension member 77 which may be a fine wire or rod- 01 equivalent device combining a high degree of tensional strength with light weight, this wire extending .down through the guide tube 29 and attached to the vibrating frame 14 oft-he balancing machine, as shown in Fig. 1. Through the parts last described the vertical vibrating movements of the T pivoted frame 14 are translated into oscillating movements of the arbor 54 and swinging movements of the indicatingpointer 58.

Overlying the front of the dial disc 46 is a recording pointer 78, the purpose of which is to record the maximum oscillations of the frame 14 which, as stated, occur at the socalled critical speed. This recording pointer 78 is manually set to its zero position indicated in Figs. Q-and 7, and is moved therefrom upwardly of the scale by the spider 56 of the indicating pointer, being so mounted as to remain fixed at the point of maximum movement which corresponds to the maximum oscillation of the indicating pointer. Describing the means for mounting and actuating the recording pointer 78, 79 designates ashort arbor disposed coaxially with the indicating arbor 54, on which the recording pointer 7 8 is mounted. One pointed end of the arbor 79 has a bearing in a correspondingly shaped seat 80 in the front face of the bearing block 52. The other pointed end'of the arbor 79 engagesa similar seat 81 in the upper end of a friction bearing plate 82. Said plate 82, as shown in Fig. 5, is formed with a widened base the central portion of which is engaged by the conical head 83 of a spring-pressed plunger 84 that, in turn, is slidably mounted in and normally pressed forwardly from a screwthreaded plunger housing 85 mounted and adjustable in the dial disc 46 and secured by a lock nut 86. 87 (Fig. 4) designates a substantially semi-circular outer mounting plate that is rigidly attached to the dial disc 46 by a pair of posts 88 and screws 89. Mounted in the lower-portion of the mounting plate 87 are a pair of fulcrum screws 90 having pointed inner ends that engage correspondingly shaped seats 91 (Fig. 5) in the outer face of the friction bearing plate 82. The thrust of the spring-pressed plunger '84 on the low r end of the bearing plate 82 tends to rock said plate on its fulcrum oints 90, thereby causing the upper end of the plate 82 to press lightly against the arbor 79, creating sufiicient friction in the bearings of the latter to hold the said arbor and its recording pointer 78 at any set position.

Referring to Figs. 7 and 8, the recording pointer 78 is formed with an inwardly bent tail piece 92 that extends through an arcuate slot 93 in the dial disc 46 concentric with the axis of the latter; and this tail piece 92 lies in the path of travel of a striker lug 94 fast pn one of the arms of the spider 56 which hes at'a right angle to the indicator pointer 58. Consequently, when the indicator pointer swings clockwise, viewing ,Figs. 2 and 7, toa point where the striker lug 94 hits the tail piece 92 of the recording pointer 78, the latter is carried along in the same direction with, and to the same extent as, the indicating pointer. It will be observed that in the arrangement shown the scale disc is equipped with two fixed scales of equal lengths, one located 90 ahead of the other on the face of the disc, and the zero points of the two scales are, therefore, 90 apart, the zero point of the indicating pointer being at the top and the zero point of the recording pointer being 90 to the left.

Hence, movement of the indicator pointer in a counter-clockwise direction is without effeet on the recording pointer, but movement of the indicator pointer in a clockwise direction from its zero point is accompanied by an equal movement in the same direction of the recording pointer, which latter remains in its moved position during the return or counterclockwise movement of the indicating pointer.

Where the dial disc 46 is exposed, the recording pointer 7 8. may be reset to. zeroor starting position by hand; but where the dial disc is protected as by the glass cover 41, mechanical means must be provided for resetting the recording pointer; and asimple device for that purpose comprises the following parts. Secured in and projecting forwardly of the outer mounting plate 87 is a fixed stud 95, rotatable on which is asleeve 96 terminating in a turning knob 97; said stud and sleeve extending through a central hole 98 in the glass cover disc 41. Fast on the inner end of the sleeve 96 is a disc 99, on the inner face of which (Fig. 8) is a pin 100. In the path of the free end of the pin 100is a lateral lug 101 on the recording pointer-7 8. Counter-clockwise turn- 2 and 7, if it is not already in that osition. The pointer reset pin 100 is constant y urged to a position wherein it is effective to reset the recording pointer from its extreme limit 108' formed with a depending tenon 113, the

of swing by a helical spring 102 (Figs. 3 and 4) anchored at one end to the sleeve 96 and at its other end to an anchor screw103 'in the outer mounting plate 87. The movements of the reset pin-100 are limited in both directions by'shoulders 104 and 105 (Fig. 5) formed. on a reset stop plate 106 that is mounted on the inner face of the outer bearing plate 87 by means of the bearing stud 95 and the spring anchor screws 103. As shown in Fig. 4, the anchor screw 103 may extend through a transverse slot 107 in the bearing plate 87, thereby providing for nice adjustment of the stop shoulders 104 and 105 of the stop plate to exact correspondence with the dial scale, thus rendering unnecessary delicate manipulation of the knob 97 when returning the recording pointer to zero.

Describing next the means for mounting and supporting the meter casing, 108 designates a vertical bracket arm (Fig. 3)]formed on its upper end with the integral attachment plate 109 secured to the ,back wall 36 as by screws 110. This attachment plate 109 IS fOI'IIlGd with a centraltapped opening 111 normally closed by a plug screw 112; said opening lying directly behind the arbor bearing plug 49, so that, by removing the plug screw 112, access isreadily had by a screw-driver to the bearing plug for adjusting the latter. The lower end of the bracket arm 108 is formed with an offset extension extension 108' and tenon 113 being made tubular for the passage of the links 75*and 77 of the tension connection from the meter to the pivoted machine frame 14. The tenon 113 has a swivel bearing in the free end of the horizontal bracket arm 114 (Fig. 2); the inner end of said bracket arm being keyed to a vertical rod 115 that is slidably mounted in suitable bearings in the bracket arms 33 and 34. The arm 114 is pressed upwardly against the bearing of the upper bracket arm 33 by a stiff compression sp mg 116 encircling the rod 115 and confine between the bracket arm 114 and the lower bracket arm 34. The lower end of the rod 115 is threaded and receives an adjusting thumb nut 117 bearing against the lower bracket arm 34. By turning the nut 117 the meter supporting arm 114 may be raised or lowered relatively to its main carrying bracket 32 The arm 116 is held against lateral swinging movement through sliding engagement of its grooved inner end -w1th a guide rod 118 extending between the arms parallel with the adjusting rod of course, cause different starting positions of the indicating pointer on the scale, it is essential, before beginning rotation of the test body, to set the indicating pointer to exact zero position. With test bodies differing but slightly in their static effects on the pivoted frame 14, this may be done by mere manipulation of the adjusting nut 117. If, when the machine is loaded, the indicator pointer lies to the right of its zero position shown in Fig. 7, it maybe quickly brought to zero position by slightly elevating the arm 114 and the meter carried thereby. If, on the other hand, when the machine is loaded, the indicator pointer lies to the left of its zero position, viewing Fig. 7, then the nut 117 will be so manipulated as to effect a lowering of the arm 114 and the meter until the indicator pointer registers zero. Iueither case, the indicator pointer having been thus adjusted to zero or starting position, as the frame 14 oscillates under the rotation of the test body thereon, the indicator pointer 58 fluctuates on both sides of its zero position. The clockwise movements of the pointer cause corresponding advance movements of the recording pointer 78, the latter being gradually advanced until the critical speed? is reached, which causes the maximum oscillation of the indicator pointer, and the posit-ion on the. scale to which the recording pointer is moved thereby designates and makes a record of the maximum amplitude of the vibrations. This having been noted, the machine is unloaded, a new test-body mounted thereon, the indicator pointer readjusted to zero position, if necessary, and the next test performed in the manner described.

pointer 58 in a counter-clockwise direction is limited at a point somewhat beyond the zero position of .the recording pointer by The swinging movement of the indicator contact of the head 69 in the lower end of the spring 70 with the upper end of the adjustable-stop bushing 76; while the swinging movement of the same pointer in a clockwise direction is similarly limited at a point somewhat beyond the terminal scale divisions through the closing of the coils of spring 70 on each other. Both of these stop positions may be varied by vertical adjustmen't of the bracket 72 on the back plate.

An' additional safeguard to prevent possible accidental bending of the indicator pointer l the bulbs light to the face of the dial.

50 ing frame 14.

through sudden overthrow resides in a pair of suitably located bumper springs 119, best shown in Fig. 6, mounted on the dial plate supporting posts 47; bumper springs of this '5 character being in common use on volt meters and ammeters'.

In order to facilitate reading of the scale and avoid the necessity of locating the instrument in favorable relation to external 10 light, I preferably equip the instrument itself with a pair of small electric lamps 120,

which are mounted in sockets 121 and project through openings in the dial filler plate 44 so as to transmit a suffused The lamp sockets 121 are herein shown as mounted in openings in the back plate 36 and held rigidly by ring bracket 122 attached to posts 123 on the inner side of the back plate 36.

Attached to the upper portion of the back mg the circuit wires being shown at 12.7

entering the lower wall of the switch box 124. This illumination of the dial of the instrument by means of lamps entirely enclosed in the case constitutes a valuable practical feature, since it makes the reading of the dial always plain, regardless of genl, eral lighting conditions.

In an instrument of the character herein described a prime necessity, to the attainment of accuracy is the reduction to the lowest'possible pointof all factors and influences, such as friction and wear, tending to retard or otherwise affect the sensitiveness and responsiveness of the moving parts to 40 the small impulses transmitted thereto and recorded thereby. The attainment of this object has been the primary consideration in the design of the present meter. The recording pointer is moved forward by impulses given it by the oscillating indicator pointer.

The impulses given to the recording pointer I by the oscillating indicator pointer arm are of such a nature with this device as to absorb but little of the energy of the oscillat- These impulses, especially when near the speed of resonance, have but a small increment from cycle to cycle of oscillation, and the contact between the arms being about at the end of travel and reversal Where the speed of the oscillating arm is lowest; the reaction between the arms is mimmized. Moreover, the oscillating arm strikes the recording arm at the end of one stroke only, being free at the other end of the cycle.

The recording arm is restrained from moving too far, and retained in each successive new position, by the friction on the bearlngs of its arbor or shaft. This friction must-not be too great, or the vibration of the oscillating frame of the machine will be damped;

machine.

while on the other hand the friction must not be too slight, or the pointer will overrun. Therefore, proper functioning of the recording and maximum indicating pointer depends on a delicate adjustment of. the re straining friction of'its bearings, and this adjustment for'friction must not only be delicately adjustable, but adjustment must also be stable so that it will not vary the slightest amount under wear on its hearings, or vibration, or changes in temperature; and at the sametime the arbor must be held in rigid alignment. I have found that these ends may be satisfactorily attained by making the arbor 79 with hardened and polished conical ends gripped under light tension be tween the bearings of soft metal. The described means for attaining this tension on the bearings, comprising a pivoted bearing platev resting on two widely separated fulcrum points makes a very rigid support for the end of the arbor, the spring pressing on the plate slightly below the line of the fulcrum points makes the pressure on the end of the shaft very light and yet positive. This'arrangement also makes a bearing for the end of the arbor that is without play sidewise or endwise, will not shift under jarring or rough handling of the instrument, automatically takes up wear in the bearing, is delicately adjustable, and will retain its adjustment indefinitely. O

Other features contributing to the sensitiveness and practical utility of the instrument arethe use of jewel bearings for the arbor of the indicator pointer, the described spring arrangement through which the cords transmitting the vibrations to the indicator arbor are continuously held under tension, the described means for transmitting the forward impulses of the indicator pointer to the recording pointer, the manually operated means for accurately resetting the recording pointer to its zero position, and the de scribed means, based on an up and down bodily adjustment of the instrument rela tively to its support, for setting the indicator pointer to its zero or starting position in accordance with variations in the neutral or rest position of the pivoted frame of the The use of two cords, such as 62 and 62', separately attached to the arbor and spaced part has the advantages over a single cord wrapped around the arbor,-that it prevents friction and wear through the cord rubbing on itself, and also prevents slip of the cord on the arbor. I

In the foregoing I have set forth one practical physical embodiment of the invention which in practice has been found to satisfactorily effectuate the stated purposes and objects thereof. Manifestly, however, many variations and changes in the details of structure and arrangement from those herein shown and described might be resorted to without involving any departure from the substance of the invention orsacrificing an of. the benefits and advantages thereo Hence, I do not limit the invention to the particular embodiment herein disclosed for purposes of illustration, but reserve all such variations, modifications and mechanical equivalents as fall Within the spirit and purview of the claims. I claim i J 1. In a recor ing' meter of the character de scribed, the co bination of a dial, a recording pointer movable over said dial, an arbor on which said pointer is mounted, said arbor being formed with cone-pointed'ends, a fixed bearing member having a conical seat for one end of said arbor, a bearing plate piv- I I oted on a pair of separated fulcrum points and formed on one side of the latter with a ao seat for the other end of said arbor, and a indicating pointer adapted to engage and iildvlance sa1d recording pointer over said 3. In an amplitude recording meter, the combination of a dial, an arbor,-means for transmitting oscillating movements to said for resetting said recording pointer to zero v position on said dial.

4. In an amplitude recording meter, the combination of a dial, an arbor, means for transmitting oscillating movements to said arbor, an indicating pointer fast on said arbor, a second arbor mounted in friction bearings, a recording pointer fast on said second arbor, a striker. lug on said indicatin pointer adapted to engage and advance sai recording pointer over said dial, manually operable means for resetting said recording pointer to zero position on said dial, and stops limiting the extent of movement of said recording pointer in both directions.

, FRANCIS T. MoDONOUGH. 

